The invention relates to support structures floating in the open sea and connected to anchors by bracing means, for wind turbines, service stations or converter stations.
Floating buoyant bodies in connection with anchors for wind turbines in the open sea are known via the document GB 2 378 679 A, as an example. The floating foundation realized for that is comprised of several buoyant bodies that are connected via radial steel struts to the tower of the wind turbine. The steel struts are arranged in a cross shape as viewed from the top and are not connected to one another. If bending forces arise on the radial steel struts, they lead to high bending moments.
A square floating foundation is known from the document WO 2007/096680 A1; the floats arranged at the corners are connected to one another via tie rods and struts to form a spatial support structure. A central, large float supports a tower that is braced via stay cables to the external floats. This solution requires considerable construction costs.
The document U.S. Pat. No. 7,156,586 B2 describes a floating support structure that has bracing leg sections going out radially from a tower. They are provided with floats on their ends. Stay cables are connected under tension between the floats and the tower to stabilize the tower position. Stress concentrations result on the base of the central tower that could lead to difficulties, but would at least increase the construction costs.
The document EP 1 288 122 A2 discloses a floating support structure in the form of a massive floating platform with several chambers that are filled with air like a diving bell and that can consequently be used to generate buoyancy. The construction of a floating foundation of that type is associated with high material costs.
The documents EP 1 876 093 A3 and DE 10 2008 003 647 A1 involve floating support structures for which floats are provided at ends radially extending from a central structure.
An offshore wind turbine is known from the document WO 2011/057 940 A2. It has a float that is connected via connection elements to the tower of the wind turbine. Furthermore, the offshore wind turbine has a counterweight at the end of the tower. The connection elements are arranged uniformly in several groups around the tower here. A lower group essentially carries the tower and two upper groups support and position the tower. The upper groups engage at points of the tower that are on top of one another. The tower can rotate with respect to the float because of the uniform distribution of the connection elements. The position of the tower therefore changes with respect to the float. At the same time, various forces arise in the connection elements because of the different angles of the connection elements with respect to the tower. A uniform distribution of forces no longer exists.
The document US 2005/0 206 168 A1 involves a foundation structure for offshore wind turbines; the tower of the wind turbine is connected via a grid structure to floats. The main elements here are struts that are distributed uniformly around the tower. A rotary movement of the tower with respect to the foundation structure is not ruled out.
The document WO 2004/055 272 A2 shows an offshore wind turbine with the possibility of creating a useful marine culture. The tower of the wind turbine is held in a float here via elements that are fastened to the tower and distributed around it in a uniform manner. In so doing, a rotary movement of the tower with respect to the float is, once again, not ruled out.
The document WO 2013/040871 A1 involves a semi-submersible floating platform with at least three floating, hollow concrete cylinders that are connected with one another via a cross-frame structure. The hollow concrete cylinders constitute the buoyant bodies for the floating platform that cut through the surface of the water.
A floating arrangement for generating energy with at least three floating units, each with equipment for generating energy, is known from the document US 2010/0219645 A1. Each of the units has a buoyant body and equipment for generating energy. The units and therefore the equipment for generating energy are arranged at the corner points of a triangle or square.